This application claims priority to an application entitled xe2x80x9cContactless Battery Chargerxe2x80x9d filed in the Korean Industrial Property Office on Jan. 5, 2001 and assigned Serial No. 2001-511, the contents of which are hereby incorporated by reference.
1. Field of the Invention
The present invention relates generally to a battery charger for use in a mobile communication terminal, and in particular, to a contactless battery charger.
2. Description of the Related Art
A mobile communication terminal such as a mobile phone, a personal digital assistant (PDA), a palm-top computer or an Internet phone, uses a rechargeable battery as an energy source. Therefore, such a mobile communication terminal requires a battery charger.
The existing battery charger for use in the palm-top computer and the mobile phone employs a contact-type charging technique, in which a battery pack gets electrical contact with the battery charger. Such a contact-type battery charger has the following disadvantages.
First, because of possible bad contact between the battery pack and the battery charger, the rechargeable battery may be insufficiently charged and may have a reduced life span. Second, when exposed to dust or moisture, the electrodes of the battery charger may get rusty, causing the bad-contact problem. Third, exposed to the exterior, the metal electrodes of the battery pack may frequently contact clothes of the user, generating static electricity, which may disrupt the operation of the communication terminal.
It is, therefore, an object of the present invention to provide a contactless battery charger, which can resolve the bad-contact problem between a battery pack and the battery charger.
To achieve the above and other objects, there is provided a contactless battery charger for use in a communication terminal including a converter and a charging unit. A converter includes a primary side of a printed circuit board (PCB) transformer. The converter converts a commercial electric power to a high-frequency square wave, applies the converted high-frequency square wave to the primary side of the PCB transformer, and controls generation of a charge current depending on charge state information provided. A charging unit includes a secondary side of the PCB transformer. The charging unit converts an electromotive force induced at the secondary side of the PCB transformer by a magnetic field generated by the square wave applied to the primary side of the PCB transformer to a DC voltage, charges a rechargeable battery with the DC voltage, and provides the charge state information to the converter.